Revegetation and Reclamation of Ash Lagoon Surfaces in Central Alberta

A number of experiments were initiated near Wabamun, Alberta to investigate methods of stabilizing ash lagoon surfaces, using revegetation and reclamation techniques, at coal-burning thermal power plants. The coal ash constitutes a poor plant growth medium since it is deficient in organic matter and many plant nutrients, contains potentially phytotoxic levels of boron, has a high pH, no ion exchange complex and is easily eroded when dry.  A bulk ameliorant trial was established to determine revegetation success
of a forage mixture seeded on an ash lagoon surface using several topsoil, minespoil and manure treatments. Results showed that all capped treatments produced a more dense plant cover than bare ash. Manure was the most effective amendment for improving forage yields.  A mulch trial was initiated to determine the effects of surface straw mulch or cultivated straw mulch treatments on forage establishment and growth. Straw mulch treatments did not significantly increase plant cover and forage yields compared to the bare ash control and inhibited seedling development on surface straw mulch treatments.  A legume trial was used to test the establishment, growth and nitrogen fixing capability of several legume species seeded on bare ash. Overall, the alfalfa, sweetclover (biennial) and birdsfoot trefoil legume species were easiest to establish, produced higher yields and fixed more nitrogen than cicer milkvetch and red clover.